# Filling path in pgfplot and pushing into background?

I'm using pgfplots to produce a plot of a closed path in the x-y plane. For reasons that are not important here, I would like to fill the closed path. That works fine, but the axes are then hidden by the filled path. How can I push the filled path into the background or the axes into the foreground? I looked at some other questions here that mention using pgflayers, but I can't find that in either the TikZ or pgfplots manuals.

MWE:

\documentclass[10pt]{article}

\usepackage{tikz}
\usepackage{fancyhdr}
\usepackage{pgfplots}

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}

\begin{document}
\thispagestyle{empty}

\begin{tikzpicture}
\begin{axis}[
axis x line=middle,
axis y line=middle,
xmin = -2.0, xmax =  2.0,
ymin = -2.0, ymax =  2.0,
]
(-1.0, -1.0)
( 1.0, -1.0)
( 1.0,  1.0)
(-1.0,  1.0)
(-1.0, -1.0)
};
\end{axis}
\end{tikzpicture}

\end{document}

-

There's a key for the axis environemnt

axis on top


which gives

\documentclass[10pt]{article}

\usepackage{pgfplots}

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}

\begin{document}
\thispagestyle{empty}

\begin{tikzpicture}
\begin{axis}[axis on top,
axis x line=middle,
axis y line=middle,
xmin = -2.0, xmax =  2.0,
ymin = -2.0, ymax =  2.0,
]
(-1.0, -1.0)
( 1.0, -1.0)
( 1.0,  1.0)
(-1.0,  1.0)
(-1.0, -1.0)
};
\end{axis}
\end{tikzpicture}

\end{document}

-
I know, but I want to avoid that so this plot is consistent in style with other, TikZ-generated, plots in which I do not use opacity. –  user1362373 Mar 20 '12 at 17:43
Great - I don't know how I missed that option. Thanks a lot. –  user1362373 Mar 20 '12 at 18:55